Speaking as a Mac user (who considers what he does to be real work), I think it would be more cutting to play on the games aspect of Windows. That really is the One Thing™ Windows has over other OSs
You have a funny definition of truth.
The rumors of the death of the desktop have been greatly exaggerated. WinXP is (finally) reaching EOL and they can't run forever even if you don't care about security. Win8 is the new Vista and people are happy with Windows 7 for now.
The PC market can't grow forever, how close it is to saturation I don't know but there is still a lot of money to be made in mature markets like autos, etc. MS needs to get its act together and defend its market share or it might end up like GM.
I'm not speaking for MS, but I think they want to be seen as a growth company, not a stable, mature company. They want to maintain their market share, but the "opportunities" for new growth probably lay elsewhere, so you'll see investment away from PCs into areas where new money can be made (while still trying to preserve old money, of course). Even the car needs a new remake to create new market share and hence opportunity; e.g. Tesla and electric cars.
By the way, OSX is hitting 15% market share in the US.
First is that they have drifted away from a basic principle that made Bill Gates a billionaire -- backwards compatibility, or at least when backwards compatibility had to be broken there was clear benefits and an upgrade or conversion path to ease the pain. Surface RT, Surface Pro, Win8, etc are just confusing choices to any customers thinking of a purchase. I'd rather just buy an iPad, quite frankly.
Secondly, Microsoft is still bitter and stinging over the old "I'm a Mac, I'm a PC" commercials. Those were epic, hilarious commercials that stuck a cord with users and that MS never countered. They should have blasted back with the truth -- yeah, Macs are cool but when you want to get real work done you use Windows. Instead they were silently stewing with resentment. Surface and the Surface marketing campaign can be summed up as MS's attempt to show the world that they are "cool" too just like Apple. But as most people know, trying to be cool is uncool and everyone laughs at the attempt. MS needs to embrace and be proud of their identity and stop trying to me-too Apple and just build products that work and run the world.